When should I deduct art material expenses for project started in one year but delivered in the following year?

I make fine art quilts and donate them to charitable organizations (e.g. the ALS Foundation) who, in turn, give the quilts to the patients they serve.  In the past week, I have purchased materials for a quilt that I just started.  It will not be donated until early 2025.  When do I take the materials deduction?  The materials receipt says 2024 but the donation will be in 2025.